Measures against water pollution in the fermentation industries.

The paper is a review of some current practices in the treatment and disposal of the more important fermentation industry effluents. Reference is made to the production of whisky and other potable spirits, malt, beer, vinegar, yeast, cider, antibiotics and vitamins. The most important means of treating distillery effluents is by recovering the soluble and some insoluble material in the liquid residue from the distillation of fermented wash. The process involves evaporation and drying to produce dry, nutritionally rich animal feeding materials by the sale of which the capital cost of the plant may be recovered. Condensate from the evaporation process contains organic acids and must be treated biologically before discharge to rivers, as must other watery residues from the distillery. Treatment may be on conventional mineral packed biological filters, on plastic filled towers or by an activated sludge process. Other methods of disposal of distillery wastes include complete biological treatment of the mixed effluents, disposal to land, to sea and to sewers. Discharges to sewers often attract special charges by the local authority. Burning wastes with the recovery of heat and ash is also practiced. Effluents from the malting process are easily treated biologically, whether on site at the maltings or, after discharging to sewers, at the local authority sewage works in admixture with sewage. Brewery effluents, mostly cooling and wash waters, are usually discharged to sewers, but some biological pre-treatment may be given on site, where plastic packed biological filter units are sometimes used. Vinegar factory effluents are also usually discharged to sewers and are easily treatable. The ease with which most fermentation wastes can be treated biologically has encouraged the industries concerned to ask local authorities to acknowledge the fact by suitably reducing charges for effluents treated at the sewage works. Yeast manufacturing effluents comprise residual wash, yeast washings etc., and are readily treatable biologically. Fears that yeast effluents cause slime growths in sewers are not substantiated in practice, but a case is described in which yeast wastes are piped separately from sewage to the disposal site. Cider effluents are easily treated biologically, either on site with additions of suitable nutrients, or in admixture with sewage. Antibiotics and vitamin fermentation effluents are sometimes difficult to treat biologically, but are often so treated and are sometimes acceptable in sewers. Recovery of solids from residual washes is practiced, with the production of material suitable for animal feeding. In the UK the tendency is for factories to be sited on estuaries or the sea coast where untreated effluent may be discharged